@emanuel-schmid or @peanutfun, this should be a quick one to review. And will fix some of the currently failing tests.

There are some administrative regions, which lead to an error when trying to create LitPop for them.
I started from an old, global LitPop object and wanted to create a new LitPop object for all region ids. The failing admin units are: ['ALA', 'ESH', 'HMD', 'PCN', 'SGS', 'UMI']
These are: Åland Islands, Western Sahara, Heard Island and McDonald Islands, Pitcairn Islands, South Georgia and the South Sandwich Islands, United States Minor Outlying Islands

Please find the code how to determine these below.

`country_names = global_litpop.gdf.region_id.unique()
iso3a_list = u_coord.country_to_iso(country_names, representation="alpha3")

info_ind = "NY.GDP.MKTP.CD"
data = []
network = []

for cntry_iso in iso3a_list:
try:
cntry_gdp = util_fin.download_world_bank_indicator(indicator=info_ind, country_code=cntry_iso, parse_dates=False)
except (ReadTimeout, RequestException):
print(f"Network issue: {cntry_iso}")
network.append(cntry_iso)
except ValueError as e:
print(f"Data/API issue for {cntry_iso}: {e}")
data.append(cntry_iso)

failing_c = []
for country in data:
print(country)
try:
exp = LitPop.from_countries(country, reference_year=2002)
except ValueError as e:
failing_c.append(country)
`